Five-field vs six-field Cron: identify the dialect first

Label the five fields

Standard five-field Cron uses minute, hour, day of month, month and day of week. It has no leading seconds field.

Write the field labels beside a copied expression. A shifted field can produce a valid expression that schedules the wrong time.

0 9 * * 1-5
minute hour day month weekday
09:00, Monday through Friday, in the scheduler's zone

Six fields need a specification

Some libraries add seconds at the front; other scheduler dialects have different fields or special tokens. Field count alone does not prove compatibility.

Nav Tools accepts standard five-field expressions. A six-field input should be translated only after checking the destination’s exact syntax.

Do not silently drop seconds

A six-field expression with nonzero seconds cannot always be represented by five-field minute-resolution Cron. Removing the first field changes the schedule.

If the source uses seconds zero, a documented conversion may be possible. For subminute jobs, use a scheduler supporting that requirement.

Verify zone and calendar rules

After mapping fields, confirm the timezone, weekday numbering and day-versus-weekday combination behavior. Those details can differ between schedulers.

Preview several runs at a fixed start instant, including a month boundary. Copy a verified expression and its assumptions together into deployment configuration.